The present invention relates to an inkjet recording apparatus, and in particular to an inkjet recording apparatus where light-hardenable ink is hardened and fixed on a recording medium by radiating light.
As an image recording apparatus capable of recording an image not only on ordinary paper or textile but a medium having an inferior ink absorption property such as a resin film, there had been developed an inkjet recording apparatus in which a nozzle provided on an end face of a recording head ejects ink to land the ink on the recording medium. At the present day, this technology is applied to various technical fields. Among them, a light-hardenable type inkjet apparatus, where light such as ultra violet light is radiated onto the ink landed on the recording medium to harden and fix the ink, has been actively developed.
In such light-hardenable type inkjet recording apparatus, because a superior manageability of ink and a high recording quality can be obtained, ultra violet light hardenable ink hardened by radiation of ultra violet light is frequently used. Also, as a light source to radiate the ultra violet light onto the ultra violet light hardenable ink to hardened, a high pressure mercury lamp or low pressure mercury lamp have been used.
However, the high pressure mercury lamp and low pressure mercury lamp usually require to be applied by high tension alternate electric power of more than 100 V, thus there was dangerousness of electrification by contacting with a high voltage power source or a circuit when an operator place the hand inside the apparatus to handle paper jamming and so forth.
In recent years, a semiconductor light emitting element in particular ultra violet light emitting diode (UVLED) is attracting attention as a light source having advantages of long life and rapid start, and various inkjet recording apparatuses using the light thereof as the ultra violet light source have been developed (for example, Patent Documents 1-7).
The semiconductor light emitting element usually has an advantage that a light intensity can be adjusted in accordance with a current value of an electric current to be supplied, and can emit light with a low voltage direct current power, thereby being expected as a solution to solve the aforesaid problems which the high pressure mercury lamp and low pressure mercury lamp possess.
Patent document: Tokkai 2004-181943
Patent document: Tokkai 2004-237588
Patent document: Tokkai 2005-104108
Patent document: Tokkai 2005-144679
Patent document: Tokkai 2005-254560
Patent document: Tokkai 2006-27235
Patent document: Tokkai 2006-27236
Meanwhile, since the light intensity can be adjusted by changing current value, to efficiently adjust the light intensity, it is often practiced that a plurality of semiconductor light emitting elements are connected in series and the current value is changed so as to adjust the light intensity of the plurality of the semiconductor light emitting elements in serial connection simultaneously. In addition, to harden the light-hardenable ink landed on the recording medium, a number of semiconductor light emitting elements are provided.
Thus, though the voltage of the direct current power applied to each semiconductor light emitting element is low, since a number of semiconductor light emitting elements are serially connected, the voltage is increased consequently. As a result, similar to the conventional high pressure mercury lamp and low pressure mercury lamp, the problem of electrification has not been solved.